As the present trend in tire-making technology continues toward the use of higher silica loadings in rubber compounds, there is a challenge to contain levels of environmentally released volatile organic compounds (VOC), especially alcohol, during compounding, processing, cure and storage of silica-reinforced rubbers.
In our U.S. patent application Ser. No. 11/387,569, filed Mar. 23, 2006, entitled “Compounding Silica-Reinforced Rubber With Low Volatile Organic Compound (VOC) Emission,” the entire disclosure of which is hereby incorporated by reference, we described the preparation of alkyl alkoxy-modified silsesquioxane (alkyl AMS) compounds and alkyl/mercaptan co-alkoxy-modified silsesquioxane (alkyl/mercaptan co-AMS) compounds that generate less alcohol than conventional alkoxysilane-containing silica-coupling and/or silica dispersing agents used in rubber compounding. It was found that the decreased amount of alcohol produced when using the alkyl AMS and alkyl/mercaptan co-AMS compounds in rubber compositions resulted in vulcanized rubber compounds having one or more improved properties such as, but not limited to, enhanced rubber reinforcement, increased polymer-filler interaction and lower compound viscosity, providing for tires having improved wet and snow traction, lower rolling resistance, increased rebound and decreased hysteresis.
However, at the time of filing the above-referenced patent application, it was unknown how to produce similar AMS compounds that also contained amino groups, i.e., an amino AMS, an amino/mercaptan co-AMS, and an amino/blocked mercaptan co-AMS. It was also unknown what effects the addition of such amino AMS and/or amino co-AMS compounds to rubber compounds would have on the properties of such rubber compounds and components of tires containing the rubber compounds.
U.S. Provisional Patent Application Ser. Nos. 61/017,932 and 61/018,213, filed Dec. 31, 2007, describe methods for making amino AMS and amino/mercaptan co-AMS compounds, and the entire disclosures of both applications are hereby incorporated by reference.